1. Field of the Invention
The present invention relates to the technical field of image processing and, more particularly, to an image processing system and method for a liquid crystal display (LCD).
2. Description of Related Art
In order to improve motion blur caused by the continuous lighting on an LCD screen, a conventional technique places a black or gray screen to provide the black or gray image between the original images to thereby simulate the pulse display feature of a CRT TV and reduce the motion blur on human eyes due to the persistence of vision. However, the image quality is reduced because the entire image brightness becomes darker and the frame flicker occurs when the black images are interlaced to the output images.
To overcome this problem, a Japanese patent publication number JP2002-351382 proposes a technique to convert an original frame signal into a double frequency frame output signal which has one frame for a low frequency output signal and the other frame for a high frequency output signal, and use a motion detector to detect an object motion vector for determining the gains of the low and high frequency output signals. FIG. 1 is a block diagram of an image processing system of a typical LCD. As shown in FIG. 1, the system includes a frame converter 110, a low pass filter 120, a low frequency gain device 130, a high pass filter 140, a high frequency gain device 150, a mixer 160, a driver 170, a display panel 180 and a motion detector 190. The motion detector 190 detects the object motion vector of an input frame s1 for determining the respective gains of the gain devices 130 and 150.
FIG. 2 is a schematic diagram of a typical operation of FIG. 1. As shown in FIG. 2, when the motion detector 190 detects no object movement in the input frame s1, it sets the gains of the gain devices 130 and 150 to one, i.e.) s_out=s_out′=1×s2L+1×s2H. When the motion detector 190 detects an object movement in the input frame s1, it sets the gain of the gain device 150, which corresponds to the double frequency frame output signal, to 0.5 and 1.5 alternately, i.e., s_out=1×s2L+0.5×s2H and s_out′=1×s2L+1.5×s2H, thereby enhancing the high frequency component. Such a way can reduce the motion image residual effect on the LCD screen, but a smear effect may occur at the object edges of a high contrast image to thereby reduce the entire image quality. Therefore, it is desirable to provide an improved image processing system and method to mitigate and/or obviate the aforementioned problems.